1. Field of the Invention
The invention concerns a sliding device for a pump having two conveyance cylinders operating in counterstroke for conveyance of viscous materials supplied to the pump from a material feeding bin, and including a C-shape curved pivot pipe, an extension pipe, and a discharge conduit. The pivot pipe extends into the material feeding bin and at its upper end is connected to the extension pipe. The extension pipe projects over the back wall of the material feeding bin essentially parallel to the conveyance cylinders and, on its end opposite the pivot pipe, is connected to the discharge conduit via a pipe rotating connection. The pivot pipe is connected for pivoting so that its lower end, preferably provided with an anti-friction ring, is caused via a reversing mechanism to connect alternatively to the openings of the conveyance cylinders which are connected to the back wall of the material supply bin.
2. Description of the Related Art
Sliding devices of this general type (DE-C-21 62 406) are particularly suitable for use as mobile cement pumps because of their compact construction, wherein the extension pipe extends over the back wall of the material supply bin and forms a connection with the conveyor mast which rests on the front portion of the chassis, and wherein the material supply bin can be easily charged or fed from the back side of the vehicle chassis. Those parts of the sliding device which are subjected to high friction wear are easily accessible from the upper side of the material supply bin and thus can be changed out in a simple matter. The pipe extending beyond the back wall of the material supply bin serves in the known sliding devices on the one hand as transport pipe for the thick materials which are often abrasive and thus is subjected to a significant amount of frictional wear. On the other hand, the extension pipe has at the same time a support bearing function for the pivot pipe. In the case of increasing wear, that is, with decreasing wall thickness in the extension pipe, the integrity of the extension pipe decreases, so that a gradually increasing risk of rupturing occurs. The rupturing danger occurs above all when heavy, highly viscous cement is conveyed, and the conveyance forces acting on the extension pipe are corresponding large. A pipe rupture in this area is a problem insofar as it occurs outside of the material supply bin and thus requires an immediate cessation of the pumping operation.